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    SubjectRe: [PATCH] hwspinlock/msm: Add support for Qualcomm MSM HW Mutex block
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    On Jul 29, 2013, at 4:40 PM, Stephen Boyd wrote:

    > On 07/29, Kumar Gala wrote:
    >>> diff --git a/Documentation/devicetree/bindings/arm/msm/tcsr-mutex.txt b/Documentation/devicetree/bindings/arm/msm/tcsr-mutex.txt
    >>> new file mode 100644
    >>> index 0000000..ddd6889
    >>> --- /dev/null
    >>> +++ b/Documentation/devicetree/bindings/arm/msm/tcsr-mutex.txt
    >
    > Maybe this should go under a new hwspinlock directory?

    Will look for Ohad to comment on this.

    >
    >>> @@ -0,0 +1,20 @@
    >>> +Qualcomm MSM Hardware Mutex Block:
    >>> +
    >>> +The hardware block provides mutexes utilized between different processors
    >>> +on the SoC as part of the communication protocol used by these processors.
    >>> +
    >>> +Required properties:
    >>> +- compatible: should be "qcom,tcsr-mutex"
    >>> +- reg: Should contain registers location and length of mutex registers
    >>> +- reg-names:
    >>> + "mutex-base" - string to identify mutex registers
    >>> +- qcom,num-locks: the number of locks/mutexes supported
    >>> +
    >>> +Example:
    >>> +
    >>> + qcom,tcsr-mutex@fd484000 {
    >
    > Maybe it should be hw-mutex@fd484000?

    again, will look for Ohad to make some comment on this.

    >>> + compatible = "qcom,tcsr-mutex";
    >>> + reg = <0xfd484000 0x1000>;
    >>> + reg-names = "mutex-base";
    >>> + qcom,num-locks = <32>;
    >>> + };
    >>> diff --git a/drivers/hwspinlock/msm_hwspinlock.c b/drivers/hwspinlock/msm_hwspinlock.c
    >>> new file mode 100644
    >>> index 0000000..c7d80c5
    >>> --- /dev/null
    >>> +++ b/drivers/hwspinlock/msm_hwspinlock.c
    >>> @@ -0,0 +1,150 @@
    >>> +/*
    >>> + * Copyright (c) 2013, The Linux Foundation. All rights reserved.
    >>> + *
    >>> + * This software is licensed under the terms of the GNU General Public
    >>> + * License version 2, as published by the Free Software Foundation, and
    >>> + * may be copied, distributed, and modified under those terms.
    >>> + *
    >>> + * This program is distributed in the hope that it will be useful,
    >>> + * but WITHOUT ANY WARRANTY; without even the implied warranty of
    >>> + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
    >>> + * GNU General Public License for more details.
    >>> + */
    >>> +
    >>> +#include <linux/err.h>
    >>> +#include <linux/kernel.h>
    >>> +#include <linux/slab.h>
    >>> +#include <linux/device.h>
    >>> +#include <linux/module.h>
    >>> +#include <linux/platform_device.h>
    >>> +#include <linux/of.h>
    >>> +#include <linux/of_address.h>
    >>> +#include <linux/of_device.h>
    >>> +#include <linux/hwspinlock.h>
    >>> +
    >>> +#include <asm/io.h>
    >
    > <linux/io.h> please.

    will change, I choice <asm/io.h> since *_relaxed are arm specific.

    >>> +
    >>> +#include "hwspinlock_internal.h"
    >>> +
    >>> +#define SPINLOCK_ID_APPS_PROC 1
    >>> +#define BASE_ID 0
    >>> +
    >>> +static int msm_hwspinlock_trylock(struct hwspinlock *lock)
    >>> +{
    >>> + void __iomem *lock_addr = lock->priv;
    >>> +
    >>> + writel_relaxed(SPINLOCK_ID_APPS_PROC, lock_addr);
    >>> + smp_mb();
    >
    > Are you sure you don't want mb() instead? What is this barrier
    > for? Comment please.

    Hopefully, Eric or Jeff can comment.

    >>> + return readl_relaxed(lock_addr) == SPINLOCK_ID_APPS_PROC;
    >>> +}
    >>> +
    >>> +static void msm_hwspinlock_unlock(struct hwspinlock *lock)
    >>> +{
    >>> + int lock_owner;
    >>> + void __iomem *lock_addr = lock->priv;
    >>> +
    >>> + lock_owner = readl_relaxed(lock_addr);
    >>> + if (lock_owner != SPINLOCK_ID_APPS_PROC) {
    >>> + pr_err("%s: spinlock not owned by Apps (actual owner is %d)\n",
    >>> + __func__, lock_owner);
    >>> + }
    >>> +
    >>> + writel_relaxed(0, lock_addr);
    >>> + smp_mb();
    >
    > Same here. What is smp_mb() for?

    Hopefully, Eric or Jeff can comment.

    >
    >>> +}
    >>> +
    >>> +static const struct hwspinlock_ops msm_hwspinlock_ops = {
    >>> + .trylock = msm_hwspinlock_trylock,
    >>> + .unlock = msm_hwspinlock_unlock,
    >>> +};
    >>> +
    >>> +static struct of_device_id msm_hwspinlock_of_match[];
    >
    > Why not just put the match table here then? Also, can it be
    > const?

    Will change and make const

    >
    >>> +static int msm_hwspinlock_probe(struct platform_device *pdev)
    >>> +{
    >>> + int ret, i, stride;
    >>> + u32 num_locks;
    >>> + struct hwspinlock_device *bank;
    >>> + struct hwspinlock *hwlock;
    >>> + struct resource *res;
    >>> + void __iomem *iobase;
    >>> + struct device_node *node = pdev->dev.of_node;
    >>> + const struct of_device_id *match;
    >>> +
    >>> + match = of_match_device(msm_hwspinlock_of_match, &pdev->dev);
    >>> + if (!match)
    >>> + return -EINVAL;
    >>> +
    >>> + ret = of_property_read_u32(node, "qcom,num-locks", &num_locks);
    >>> + if (ret || (num_locks == 0))
    >
    > Drop useless ().

    done

    >
    >>> + return -ENODEV;
    >>> +
    >>> + res = platform_get_resource_byname(pdev, IORESOURCE_MEM, "mutex-base");
    >>> + iobase = devm_ioremap_resource(&pdev->dev, res);
    >>> + if (IS_ERR(iobase))
    >>> + return PTR_ERR(iobase);
    >>> +
    >>> + bank = devm_kzalloc(&pdev->dev,
    >>> + sizeof(*bank) + num_locks * sizeof(*hwlock), GFP_KERNEL);
    >>> + if (!bank)
    >>> + return -ENOMEM;
    >>> +
    >
    > Style Nit: Maybe we could grow a local variable to get this to be
    > one line.
    >
    > size_t array_size;
    >
    > array_size = num_lock * sizeof(*hwlock);
    > bank = devm_kzalloc(&pdev->dev, sizeof(*bank) + array_size, GFP_KERNEL);

    done

    - k

    >
    > --
    > Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum,
    > hosted by The Linux Foundation
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    --
    Employee of Qualcomm Innovation Center, Inc.
    Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, hosted by The Linux Foundation



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